Method for analyzing active ingredients of cannabis and control program for liquid chromatograph

ABSTRACT

In an LC system using an ODS column ( 15 ) and UV detector ( 17 ), a cannabis-derived sample is analyzed by gradient elution using a phosphoric acid aqueous solution and phosphoric-acid-containing methanol. A control unit ( 3 ) regulates the openings of solenoid valves in a mixer ( 12 ) so that the increase rate of the mixture ratio of the phosphoric-acid-containing methanol in a second part of the analysis period is higher than in a first part. By this operation, ten active ingredients (including Total THC, Total CBD and CBN) contained in cannabis can be satisfactorily separated within an analysis time which is equal to or even shorter than approximately 30 minutes. Each ingredient separated by the column ( 15 ) is detected by the UV detector ( 17 ). An active ingredient identification processor ( 22 ) identifies the ten active ingredients based on the retention times of the peaks on a chromatogram created from the detection signals.

TECHNICAL FIELD

The present invention relates to an analysis method for theidentification and/or quantitative determination of active ingredientscontained in cannabis, as well as a computer program for controlling aliquid chromatograph for such an analysis. It should be noted that theterm “cannabis” in the present description includes various forms ofCannabis sativa, such as the corolla or leaves of hemp (marijuana) in anunprocessed form, those in a dried form, as well as their extractivesthat are processed into a resin or liquid form.

BACKGROUND ART

While cannabis is banned by law in many countries including Japan, thereare some countries in which its use is legalized, such as theNetherlands and Brazil. In the United States of America, its use hasbeen legalized in some states for medical purposes only. An extremelysmall number of states have even legalized the use of cannabis fortasting purposes as well as for medical purposes. There are also somereports stating that cannabis is far less toxic or less addictive thanother kinds of drugs. Its effects as a medical agent have also beenwidely recognized. Accordingly, despite the fact that many people arestill against the removal of the existing ban, the general trend in theUSA is toward the legalization of cannabis.

It has been commonly known that cannabis contains various compounds,which are generally called “cannabinoids”, which can act as activeingredients having pharmacological effects on human bodies. The kindsand amounts of active ingredients contained in cannabis vary dependingon such conditions as the origin of the marijuana and its plantingconditions (e.g. the kinds and/or amounts of fertilizers, growingseason, and so on). Accordingly, in the American states in whichcannabis is legalized, it has been necessary to accurately identifyactive ingredients contained in cannabis and determine their quantities.There are many commissioned analytical institutions undertaking suchtests and analyses. However, at present, no official method isspecified, and no analysis method has yet been established. The currentsituation is such that commissioned analytical institutions (or similarorganizations) need to individually determine analysis methods by trialand error. Therefore, the analysis is not always highly reliable. It isalso difficult to compare analysis results provided by differentcommissioned analytical institutions.

In general, gas chromatographs (GC), gas chromatograph massspectrometers (GC-MS), liquid chromatographs (LC), liquid chromatographmass spectrometers (LC-MS) and various other analyzing devices have beenused for the testing and analysis of active ingredients of cannabis.

GC-MS and LC-MS have also been often used for the identification of suchsubstances as illegal drugs (e.g. synthetic cannabinoids) and toxicants(for example, see Patent Literature 1). In an analysis using a GC-MS orLC-MS, even when there are a plurality of compounds which have beenincompletely separated by the GC or LC, i.e. even when the sample whichhas undergone the separation process by the GC or LC contains an activeingredient and foreign substance mixed together or a plurality of activeingredients mixed together, the mass spectrometer serving as thedetector can separate those components according to their mass-to-chargeratios and detect each component. Such an analysis has the advantagethat a number of active ingredients can be assuredly separated, and eachcomponent can be accurately detected.

However, as compared to GC or LC, GC-MS and LC-MS are considerablyexpensive. In general, commissioned analytical institutions make aprofit by efficiently operating a number of devices. For suchinstitutions, the cost of introducing an expensive device will impose aconsiderable amount of financial burden. Another problem is that GC-MSand LC-MS are more complex in operation and manipulation than GC or LC,so that they cannot be easily operated by workers who are not familiarwith these analyzing tasks. In comparison with GC-MS or LC-MS, GC and LCare considerably less expensive as well as easier to operate andmanipulate. However, they are also less capable of separating aplurality of compounds. Therefore, it is difficult to analyze, at onetime, a large number of active ingredients contained in cannabis. For anidentification and quantitative determination of a large number ofactive ingredients, it is normally necessary to perform a plurality ofanalyses under different analysis conditions. Therefore, the analysisrequires a considerable amount of time, so that the analyzing efficiencyis low.

CITATION LIST Patent Literature

Patent Literature 1: JP 2015-52570 A

SUMMARY OF INVENTION Technical Problem

The present invention has been developed to solve the previouslydescribed problems. Its objective is to provide a method for analyzingthe active ingredients of cannabis, as well as a control program for thesame method, by which an accurate identification and quantitativedetermination of a plurality of particularly important ingredients amongthe active ingredients of cannabis can be performed using a device thatis comparatively inexpensive as well as easy to manipulate and operate.

Solution to Problem

The present invention developed for solving the previously describedproblems is a method for analyzing a plurality of active ingredientscontained in cannabis using a liquid chromatograph, the methodincluding:

a) a separation step, in which a plurality of components contained in aliquid sample are separated from each other by gradient elution using anODS column as a column, with a phosphoric acid aqueous solution andphosphoric-acid-containing methanol as mobile phases;

b) a detection step, in which each component separated in the separationstep is detected with a detector which is either an ultravioletspectrometric detector or photodiode array detector; and

c) an identification step, in which a plurality of predetermined activeingredients are identified based on the retention times of the peaksobserved on a chromatogram created based on a detection result obtainedin the detection step.

In the method for analyzing the active ingredients of cannabis accordingto the present invention, a plurality of components in a liquid sampleare separated from each other by reversed-phase liquid chromatography inthe separation step. In the detection step, the separated components aredetected with a detector which is either an ultraviolet spectrometricdetector or photodiode array detector. That is to say, in the detector,the absorbance of a specific wavelength of light by the component in theeluate from the column is measured to obtain detection signalscorresponding to the concentration of that component. In theidentification step, a chromatogram is created based on the detectionresult obtained with the detector, to eventually identify a plurality ofspecific active ingredients based on the retention times of the peaksobserved on the chromatogram.

The predetermined active ingredients to be identified in the analysismethod of the active ingredients of cannabis according to the presentinvention may include the following ten ingredients:tetrahydrocannabivarin (THCV), cannabidiol (CBD), cannabigerol (CBG),cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), cannabinol (CBN),Δ9-tetrahydrocannabinol (d9-THC), Δ8-tetrahydrocannabinol (d8-THC),cannabichromene (CBC), and Δ9-tetrahydrocannabinolic acid A (THCA-A).

While active ingredients of cannabis other than the ten aforementionedones are also known, it is the quantitative determination of Total THC(d9-THC, d8-THC and THCA-A), Total CBD (CBD and CBDA) and CBN that isparticularly in high demand for analysis. A method capable of analyzingthe ten aforementioned ingredients can completely cover these highlydemanded ingredients as well as exhaustively cover the ingredientsdesignated as analysis targets in three or more organizations among themajor commissioned analytical institutions in the USA.

Some active ingredients of cannabis easily undergo thermaldecarboxylation. Specifically, THCA-A turns into d9-THC by thermaldecarboxylation, while CBDA turns into CBD by thermal decarboxylation.In the case of a gas chromatograph, the liquid sample to be supplied tothe column is normally vaporized in a sample vaporization chambermaintained at high temperatures, in which process at least some of theaforementioned active ingredients may possibly be decomposed and towerthe preciseness of the quantitative determination. By comparison, themethod for analyzing the active ingredients of cannabis according to thepresent invention, which uses a liquid chromatograph, does not cause theaforementioned kind of thermal denaturing or modification of activeingredients in the sample, so that a precise identification andquantitative determination can be performed even for ingredients thateasily undergo thermal decarboxylation.

Some of the ten aforementioned ingredients have considerably similarchemical structures and accordingly have close retention times.Normally, it is difficult to completely separate those ingredients (i.e.with a degree of separation of 1 or higher). In particular, d9-THC andd8-THC, which are considerably similar in chemical structure, have beendifficult to be detected in a completely separated form. This problemcan be solved by the method for analyzing the active ingredients ofcannabis according to the present invention; the ten aforementionedingredients can be satisfactorily separated from each other by combiningan ODS column with an appropriate gradient elution using a phosphoricacid aqueous solution and phosphoric-acid-containing methanol as themobile phases. This means that a single analysis is enough to identifythe ten aforementioned ingredients and determine the presence or absenceof each ingredient. Furthermore, for example, the quantity of eachingredient can be precisely determined based on the area value of a peakon a chromatogram.

In the method for analyzing the active ingredients of cannabis accordingto the present invention, the mixture ratio of thephosphoric-acid-containing methanol in the gradient elution in theseparation step may preferably be changed so that the mixture ratio isincreased at a first increase rate and subsequently at a second increaserate which is higher than the first increase rate.

More specifically, the method for analyzing the active ingredients ofcannabis according to the present invention can be performed so that atleast two ingredients, i.e. THCV and CBD, are separated from each otherand sequentially eluted from the column within the period of time wherethe mixture ratio of the phosphoric-acid containing methanol is beingincreased at the first increase rate, whereas seven ingredients, i.e.CBDA, CBGA, CBN, d9-THC, d8-THC, CBC and THCA-A are separated from eachother and sequentially eluted from the column within the period of timewhere the mixture ratio of the phosphoric-acid containing methanol isbeing increased at the second increase rate. As for CBG, the elutionfrom the column can be made to occur within the period of time where themixture ratio of the phosphoric-acid containing methanol is beingincreased at the first increase rate, within the period of time wherethe mixture ratio is being increased at the second increase rate, orwithin a period of time overlapping the two aforementioned periods oftime.

By the two-stage setting of the changing rate of the mixture ratio ofthe mobile phases during the gradient elution, the ten aforementionedingredients can be satisfactorily separated, and the elution of eachingredient from the column can be quickly completed. Therefore, theanalysis time can be reduced. As will be described later, an experimentconducted by the present inventor has demonstrated that the tenaforementioned ingredients can be satisfactorily analyzed withinapproximately 30 minutes or shorter analysis time per one cycle in thecase of sequentially analyzing a large number of samples.

In the method for analyzing the active ingredients of cannabis accordingto the present invention, the first and second increase rates at whichthe mixture ratio of the phosphoric acid aqueous solution andphosphoric-acid-containing methanol is changed during the gradientelution, the relationship of the two rates as well as other conditionsdepend on the phosphoric acid concentration of each mobile phase, flowvelocity of the mixed mobile phase, size of the column and otherfactors. In order to satisfactorily separate the ten aforementionedingredients within approximately 30 minutes or shorter analysis time,the second increase rate should preferably be higher than the firstincrease rate, as stated earlier. Specifically, the second increase rateshould preferably be approximately 3-4 times as high as the firstincrease rate.

In the method for analyzing the active ingredients of cannabis accordingto the present invention, an ODS column is used as the column. In ananalysis using an ODS column, the particle size of the packing material,pore size of the particles and other related parameters of the ODScolumn affect the separation capability (e.g. theoretical plate number)and analysis time. Accordingly, in the method for analyzing the activeingredients of cannabis according to the present invention, an ODScolumn filled with a packing material having a particle diameter of 2.2μm and particle-pore size of 8 nm may preferably be used as the column.

The use of the packing material whose particle size and pore size aresmaller than those of a commonly used standard ODS column (with aparticle size of 5 μm and pore size of 12 nm) makes it possible torealize a high theoretical plate number and satisfactorily isolate eachingredient while reducing the column length to shorten the analysistime.

In the method for analyzing the active ingredients of cannabis accordingto the present invention employs, an ultraviolet spectrometric detectoror PDA detector, both being capable of directly detecting components ina solution (while maintaining the liquid form used as the detector. Thedetection wavelength of the detector may preferably be 220 nm.

The control program for a liquid chromatograph according to the presentinvention is a control program for controlling an operation of a liquidchromatograph including: a mobile phase mixer for regulating the mixtureratio of a first mobile phase and a second mobile phase; an injector forinjecting a liquid sample into a mixed mobile phase prepared by themobile phase mixer; a column for separating components contained in theinjected liquid sample; and a detector for detecting a component in aneluate exiting from the column, so as to analyze a plurality of activeingredients contained in cannabis using this liquid chromatograph, thecontrol program characterized by performing:

a) a sample injection step, in which the injector is operated so as toinject the liquid sample into the mixed mobile phase while the mobilephase mixer is controlled so that a mixture ratio of the first mobilephase which is the phosphoric acid aqueous solution and the secondmobile phase which is phosphoric-acid-containing methanol is maintainedin a predetermined state;

b) a gradient elution step, in which the mobile phase mixer iscontrolled so that, after the liquid sample is injected into the mixedmobile phase in the sample injection step, a mixture ratio of the secondmobile phase is increased at a first increase rate for a predeterminedperiod of time, and subsequently, the mixture ratio of the second mobilephase is increased at a second increase rate which is higher than thefirst increase rate.

The control program for a liquid chromatograph according to the presentinvention is a program for operating a computer (which may be a commonlyused personal computer configured for control operations or dedicatedcomputer embedded in the device) for controlling the mobile phase mixer,injector and other elements of a liquid chromatograph. This programshould include a time program for the gradient elution showing therelationship between the mixture ratio of the mobile phases or theopening of a valve for achieving that mixture ratio and the passage oftime. For example, such a program can be offered to users in a packagedform (e.g. CD-ROM or DVD-ROM) or through the Internet or similarcommunication lines.

The control computer built in or connected to a liquid chromatographcontrols the operations of the relevant sections according to thecontrol program for a liquid chromatograph according to the presentinvention. For example, in the mobile phase mixer, the openings of thesolenoid valves for allowing the passage of the first and second mobilephases are individually regulated with the passage of time so as to sendthe column a mixed mobile phase in which the mixture ratio of the twomobile phases gradually changes. By combining such a gradient elutionwith an ODS column, a plurality of major ingredients contained incannabis, or specifically, the ten aforementioned ingredients can besatisfactorily separated from each other.

Advantageous Effects of the Invention

With the method for analyzing the active ingredients of cannabis as wellas a control program for a liquid chromatograph according to the presentinvention, it is possible to identify a plurality of major activeingredients contained in cannabis and determine their quantities by asingle analysis using a liquid chromatograph which is comparativelyinexpensive and easy to operate and manipulate. Therefore, a system foranalyzing the active ingredients of cannabis can be constructed at a lowcost. Users who have introduced such a system do not need to manuallyperform complex tasks, such as the determination of analysis conditions;after the introduction of the system, users can promptly perform ananalysis with simple operations that do not require burdensomeexercises. Since the identification and quantitative determination ofmajor active ingredients can be precisely performed within a shortanalysis time, a highly reliable analysis result can be obtained with ahigh level of throughput.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram or one embodiment of an LCsystem for carrying out a method for analyzing the active ingredients ofcannabis according to the present invention.

FIG. 2 is a diagram showing one example of the time program for thegradient elution in the LC system of the present embodiment.

FIG. 3 is a graph showing measured examples of the chromatogram obtainedby a measurement performed for a standard sample (STD) in which the tenmajor ingredients contained in cannabis were mixed, and for two realsamples (SMP A and SMP B), using the LC system the present embodiment.

DESCRIPTION OF EMBODIMENTS

One mode of the method for analyzing the active ingredients of cannabisaccording to the present invention is described with reference to theattached drawings. FIG. 1 is a schematic configuration diagram of oneembodiment of an LC system for carrying out the method for analyzing theactive ingredients of cannabis according to the present invention.

As shown in FIG. 1, this LC system includes a measurement unit 1, dataprocessing unit 2, control unit 3, operation unit 4 and display unit 5.

The measurement unit 1 is a high-performance liquid chromatograph(HPLC), which includes: mobile phase containers 11A and 11B whichrespectively hold different mobile phases (which are hereinafter called“mobile phases A and B”); a mixer 12 including a plurality ofvariable-opening solenoid valves for mixing the two mobile phases A andB at a predetermined mixture ratio; a liquid-sending pump 13 for drawingand supplying the mobile phases A and B from the mobile phase containers11A and 11B, respectively, via the mixer 12; an injector 14 forinjecting an amount of liquid sample into the mobile phase supplied fromthe liquid-sending pump 13; a column 15 for temporally separating thecomponents (including active ingredients and foreign substances) in theinjected liquid sample; a column oven 16 for controlling the temperatureof the column 15; an ultraviolet spectrometric detector (UV detector) 17for detecting a component in an eluate coming from the exit port of thecolumn 15; and an analog-to-digital converter (ADC) 18 for sampling thedetection signals from the ultraviolet spectrometric detector 17 atpredetermined intervals of sampling time and for converting thosesignals into digital data.

The data processing unit 2 includes, as its functional blocks, a datacollector 21, active ingredient identification processor 22, and activeingredient quantity determination processor 23. This unit processes thedetection data obtained with the ultraviolet spectrometric detector 17and digitized by the ADC 18, so as to identify active ingredients in theliquid sample and determine their quantities. The controller 3 has abuilt-in storage section, in which a cannabis analysis control program31 is stored. According to this program, a CPU and other devices in thecontrol unit 3 appropriately control relevant sections of themeasurement unit 1 as well as the data processing unit 2 to performanalysis operations which will be described later. The operation unit 4allows operators (users) to command the control unit 3 to initiate themeasurement or perform other operations. The display unit 5 is used toshow analysis results and other kinds of information.

In the LC system of the present embodiment, a phosphoric acid aqueoussolution is contained as mobile phase A in the mobile phase container11A, while phosphoric-acid-containing methanol is contained as mobilephase B in the mobile phase container 11B. In the present embodiment,the concentration of the phosphoric acid aqueous solution is 0.085%(v/v). The concentration of the phosphoric-acid-containing methanol isalso 0.083% (v/v).

The column 15 is an OSD column for the reversed-phase LC. In the presentembodiment, the column has a length (L) of 75 mm and inner diameter(I.D.) of 3.0 mm. The particle size of the packing material is 2.2 μm.The particle-pore size is 8 nm. As a specific example, a columnmanufactured by Shimadzu Corporation under the name of “Shim-pack XR-ODSII” can be used as the column 15.

The ultraviolet spectrometric detector 17 has a detection cell throughwhich the eluate is passed. A predetermined wavelength of light is castinto the eluate in the detection cell, and the intensity of theresultant transmitted light is detected to obtain, as the detectionsignal, the absorbance of light by the eluate. This ultravioletspectrometric detector 17 may be an ultraviolet-visible spectrometricdetector. A photodiode array detector may also be used in place of theultraviolet spectrometric detector 17. In any case, a detector capableof directly detecting components in a solution is suitable, since amobile phase which is a phosphoric-acid-containing solution isnon-volatile; a detector which requires vaporization of the eluate isunsuitable in such a case.

The LC analysis conditions specified in the cannabis analysis controlprogram 31 in the LC system of the present embodiment are as follows:

Flow velocity of the mobile phase: 1.0 mL/min

Gradient elution condition, in terms of the mixture ratio of mobilephase B: 60% (0-5 min)—72% (at 16 min)—95% (22-24 min)—60% (25-30 min)

Amount of injected liquid sample: 5 μL

Detection wavelength: 220 nm

Column oven temperature: 50° C.

Detector cell temperature: 40° C.

FIG. 2 graphically shows the time program in the gradient elutioncondition. As shown in FIG. 2, the mixture ratio of mobile phase B isincreased from 60% to 72% at a rate of approximately 1.1%/min for 11minutes (period “a”) after the elapsed time from the sample injectionpoint (at 0 minutes) reaches 5 minutes until the elapsed time reaches 16minutes. Subsequently, the mixture ratio of mobile phase B is increasedfrom 72% to 95% at a rate of approximately 3.8%/min for 6 minutes(period “b”) after the elapsed time from the sample injection pointreaches 16 minutes until the elapsed time reaches 22 minutes. Theincrease rate of the mixture ratio of mobile phase B within period “b”is approximately 3.5 times as high as that of the mixture ratio ofmobile phase B within period “a”. In this manner, by changing theincrease rate of the mixture ratio of mobile phase B in two stages sothat the rate becomes higher in the second stage, a satisfactorycapability of separating a plurality of active ingredients is ensuredwhile the analysis time is made to be as short as possible.

The active ingredients of cannabis to be analyzed in the LC system ofthe present embodiment are the following ten ingredients:tetrahydrocannabivarin (THCV), cannabidiol (CBD), cannabigerol (CBG),cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), cannabinol (CBN),Δ9-tetrahydrocannabinol (d9-THC), Δ8-tetrahydrocannabinol (d8-THC),cannabichromene (CBC), and Δ9-tetrahydrocannabinolic acid A (THCA-A). Asalready noted, no official method for the analysis of the activeingredients of cannabis is specified in the USA. Therefore, a study hasbeen conducted to reveal what kinds of active ingredients are designatedas analysis targets by major existing commissioned analyticalinstitutions, and the ten aforementioned ingredients have been selectedon the assumption that any active ingredient designated as an analysistarget by three or more organizations should be considered to be a majoractive ingredient.

Next, a procedure for analyzing a sample in the LC system of the presentembodiment is described.

As noted earlier, during the analysis, the control unit 3 controls themeasurement unit 1 and data processing unit 2 according to the cannabisanalysis control program 31. For example, when a command to initiate themeasurement is issued from the operation unit 4, the control unit 3receives this command and controls the mixer 12 so that mobile phases Aand B are mixed at a predetermined initial mixture ratio (in the presentexample, 60% in terms of the mixture ratio of mobile phase B) whileoperating the liquid-sending pump 13 so that the flow velocity of themixed mobile phase is maintained at the aforementioned value (in thepresent example, 1.0 mL/min). As a result, the mixed mobile phase havingthe aforementioned initial mixture ratio is supplied at a fixed flowvelocity through the injector 14 to the column 15.

According to a command from the control unit 3, the injector 14 injectsthe aforementioned amount (5 μL) of liquid sample into the mobile phaseat a predetermined timing. Simultaneously with the sample injection, thedata collector 21 in the data processing unit 2 begins to collect dataobtained by digitizing the detection signals of the ultravioletspectrometric detector 17. The liquid sample injected from the injector14 is carried into the column 15 by the flow of the mobile phase. Whilethe sample is passing through the column 15, the components in thesample are temporally separated. The components separated in the column15 sequentially exit from the exit port of the column 15 and passthrough the detection cell of the ultraviolet spectrometric detector 17.The ultraviolet spectrometric detector 17 casts a predeterminedwavelength (in the present example, 220 nm) of light into the eluatepassing through the detection cell, detects the intensity of theresultant transmitted light, and obtains the absorbance of light by theeluate as the detection signal. This detection signal is digitized andstored in the data collector 21 as the detection data.

With the passage of time from the sample injection point, the controlunit 3 regulates the openings of the solenoid valves in the mixer 12according to the time program as shown in FIG. 2. Specifically, duringthe periods “a” and “b”, the opening of the solenoid valve for mobilephase A is gradually decreased, while that of the solenoid valve formobile phase B is gradually increased. Consequently, the mixture ratioof mobile phase B increases while the flow velocity is constantlymaintained. As the mixture ratio of mobile phase B increases, theelution power becomes stronger. In this process, the elution power isnot merely made to be gradually stronger; the elution power is changedat a higher rate in the second part of the analysis period than in thefirst part, so as to achieve both sufficient separation and acceleratedelution of the components elated in the second part while ensuring asatisfactory degree of separation of the components eluted in the firstpart.

In practice, after the elution of the last one of the ten ingredients iscompleted within period “b”, the concentration is reset from the finalvalue (mixture ratio of 95%) to the initial value fixture ratio of 60%),and a sufficient length of equilibrium time is provided before thecompletion of one analyzing cycle.

The injector 14 allows for a continuous analysis in which a large numberof prepared samples are sequentially injected into the mobile phase. Insuch a continuous analysis, the next analysis is subsequently performedafter one analyzing cycle as just described is completed.

FIG. 3 is a graph showing measured examples of the chromatogram obtainedby a measurement performed for a standard sample (STD) in which the tenaforementioned ingredients were mixed, and for two real samples (SMP Aand SMP B), using the LC system of the present embodiment. Real sampleSMP A was a corolla sample of cannabis which contained a high amount ofTotal CBD, while real sample SMP B was a corolla sample of cannabiswhich contained a high amount of Total THC. Needless to say, thestandard sample contains no foreign substances other than the tenaforementioned active ingredients, while the real samples containvarious foreign substances and other active ingredients different fromthe ten aforementioned active ingredients (those different activeingredients can also be regarded as foreign substances). Therefore, itis important to he capable of not only sufficiently separating the tenactive ingredients from each other hut also sufficiently separating theten active ingredients from other components.

As can be seen in the chromatogram of the standard sample in FIG. 3, thepeaks which respectively correspond to the ten ingredients aresufficiently separated from their respective neighboring peaks. It canbe seen that the peak which corresponds to d9-THC (No. 7) and one whichcorresponds to d8-THC (No. 8), which are particularly difficult to beseparated, are also satisfactorily separated from each other.

In the chromatogram of real sample SMP A in FIG. 3, the peakscorresponding to the abundant ingredients, CBD and CBDA, are observedwith high intensities at the same locations (retention times) as thepeaks corresponding to CBD and CBDA on the chromatogram of the standardsample. By comparison, in the chromatogram of real sample SMP B in FIG.3, the peak corresponding to the abundant ingredient, THCA-A, isobserved with a high intensity at the same location (retention time) asthe peak corresponding to THCA-A on the chromatogram of the standardsample. It can also be recognized that real samples SMP A and SMP B haveadditional peaks at different positions from the peaks corresponding tothe ten aforementioned ingredients. The graph demonstrates that thoseadditional peaks have also been satisfactorily separated from the peakscorresponding to the ten ingredients.

The data obtained by the analysis in the previously described manner arestored in the data collector 21 of the data processing unit 2.Accordingly, after the completion of or in the middle of the analysis,the active ingredient identification processor 22 creates a chromatogramas shown in FIG. 3 based on the obtained data, detects each peak on thechromatogram according to a predetermined algorithm, and compares theretention time of the peak with those of the ten previously registeredactive ingredients, to identify the component corresponding to thatpeak. A peak which does not correspond to any of the ten activeingredients may be judged as unidentified, or other libraries (or thelike) may additionally be referenced to continue the compoundidentification process as extensively as possible. Meanwhile, for eachingredient which has been identified (i.e. whose presence has beenconfirmed) among the ten ingredients, the active ingredient quantitydetermination processor 23 computes the area value of the peak andcalculates a quantitative value from the computed value with referenceto a calibration curve included in the cannabis analysis control program31. The control unit 3 displays the identification result andquantitative determination result on the display unit 5.

As shown in FIG. 3, the ten active ingredients as the analysis targetscan be satisfactorily separated from each other, and the other foreignsubstances can also be satisfactorily separated from the ten activeingredients. Accordingly, it is possible to precisely identify eachactive ingredient based on its retention time, and to accuratelydetermine the quantitative value of the identified ingredient.

An experiment conducted by the present inventor has confirmed that theanalysis of the ten active ingredients can be successfully completedwithin 30 minutes or shorter analysis time by using the LC system of theprevious embodiment. It has also been confirmed that an analysisaccording to the following specifications can be successfully performed:

Lower limit of quantitative determination: 0.7 mg/L or lower for allactive ingredients.

Mutual separation of active ingredients: the degree of separation shouldbe 1.8 or higher.

Separation of active ingredients from foreign substances originatingfrom real sample: the degree of separation should be 1.2 or higher.

Linearity of calibration curve: the linearity contribution ratio (R²)should be 0.999 or higher.

Carryover: the carryover of each active ingredient should be less than0.1%.

The numerical values presented in the previous embodiment, such as thesize of the column 15 and LC analysis conditions, are mere examples andcan be appropriately changed.

The LC system of the previous embodiment has the ten aforementionedactive ingredients designated as the analysis targets. Needless to say,some of those ingredients may be excluded from the analysis targets. Theopposite is also naturally possible; i.e. other active ingredients orforeign substances which are separable from the ten active ingredientsmay additionally be identified along with the ten ingredients.

Furthermore, it is evident that the previous embodiment is a mereexample of the present invention and can be appropriately changed ormodified within the spirit of the present invention.

REFERENCE SIGNS LIST

-   1 . . . Measurement Unit-   11A, 11B . . . Mobile Phase Container-   12 . . . Mixer-   13 . . . Liquid-Sending Pump-   14 . . . Injector-   15 . . . Column-   16 . . . Column Oven-   17 . . . Ultraviolet Spectrometric Detector (UV Detector)-   18 . . . Analog-to-Digital Converter (ADC)-   2 . . . Data Processing Unit-   21 . . . Data Collector-   22 . . . Active Ingredient Identification Processor-   23 . . . Active Ingredient Quantity Determination Processor-   3 . . . Control Unit-   31 . . . Cannabis Analysis Control Program-   4 . . . Operation Unit-   5 . . . Display Unit

1. A method for analyzing a plurality of active ingredients contained incannabis using a liquid chromatograph, the method comprising: a) aseparation step, in which a plurality of components contained in aliquid sample are separated from each other by gradient elution using anODS column as a column, with a phosphoric acid aqueous solution andphosphoric-acid-containing methanol as mobile phases; b) a detectionstep, in which each component separated in the separation step isdetected with a detector which is either an ultraviolet spectrometricdetector or photodiode array detector; and c) an identification step, inwhich a plurality of predetermined active ingredients are identifiedbased on retention times of peaks observed on a chromatogram createdbased on a detection result obtained in the detection step.
 2. Themethod for analyzing active ingredients of cannabis according to claim1, wherein: the plurality of predetermined active ingredients to beidentified include following ten ingredients: tetrahydrocannabivarin(THCV), cannabidiol (CBD), cannabigerol (CBG), cannabidiolic acid(CBDA), cannabigerolic acid (CBGA), cannabinol (CBN),Δ9-tetrahydrocannabinol (d9-THC), Δ8-tetrahydrocannabinol (d8-THC),cannabichromene (CBC), and Δ9-tetrahydrocannabinolic acid A (THCA-A). 3.The method for analyzing active ingredients of cannabis according toclaim 2, wherein: a mixture ratio of the phosphoric-acid-containingmethanol in the gradient elution in the separation step is changed sothat the mixture ratio is increased at a first increase rate andsubsequently at a second increase rate which is higher than the firstincrease rate.
 4. The method for analyzing active ingredients ofcannabis according to claim 3, wherein: at least two ingredients, i.e.THCV and CBD, are separated from each other and sequentially eluted fromthe column within a period of time where the mixture ratio of thephosphoric-acid containing methanol is being increased at the firstincrease rate, whereas seven ingredients, i.e. CBDA, CBGA, CBN, d9-THC,d8-THC, CBC and THCA-A are separated from each other and sequentiallyeluted from the column within a period of time where the mixture ratioof the phosphoric-acid containing methanol is being increased at thesecond increase rate.
 5. The method for analyzing active ingredients ofcannabis according to claim 3, wherein: the second increase rate is 3-4times as high as the first increase rate.
 6. The method for analyzingactive ingredients of cannabis according to claim 1, wherein: the columnis an ODS column filled with a packing material having a particlediameter of 2.2 μm and a particle-pore size of 8 nm.
 7. The method foranalyzing active ingredients of cannabis according to claim 1, wherein:the detection wavelength of the detector is 220 nm.
 8. A non-transitorycomputer-readable medium storing a control program for controlling anoperation of a liquid chromatograph including: a mobile phase mixer forregulating a mixture ratio of a first mobile phase and a second mobilephase; an injector for injecting a liquid sample into a mixed mobilephase prepared by the mobile phase mixer; a column for separatingcomponents contained in the injected liquid sample; and a detector fordetecting a component in an eluate exiting from the column, so as toanalyze a plurality of active ingredients contained in cannabis usingthis liquid chromatograph, the control program characterized byperforming: a) a sample injection step, in which the injector isoperated so as to inject the liquid sample into the mixed mobile phasewhile the mobile phase mixer is controlled so that a mixture ratio ofthe first mobile phase which is the phosphoric acid aqueous solution andthe second mobile phase which is phosphoric-acid-containing methanol ismaintained in a predetermined state; b) a gradient elution step, inwhich the mobile phase mixer is controlled so that, after the liquidsample is injected into the mixed mobile phase in the sample injectionstep, a mixture ratio of the second mobile phase is increased at a firstincrease rate for a predetermined period of time, and subsequently, themixture ratio of the second mobile phase is increased at a secondincrease rate which is higher than the first increase rate.
 9. Thecomputer-readable medium according to claim 8, wherein: the secondincrease rate is 3-4 times as high as the first increase rate.
 10. Themethod for analyzing active ingredients of cannabis according to claim4, wherein: the second increase rate is 3-4 times as high as the firstincrease rate.